class_docstr: A bridge that does not pass any information between encoder and decoder
  and sets the initial decoder state to 0. The input function is not modified.
code: def _create(self):
      zero_state = nest.map_structure(
          lambda x: tf.zeros([self.batch_size, x], dtype=tf.float32),
          self.decoder_state_size,
      )
      return zero_state
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import abc
  from pydoc import locate
  import six
  import numpy
  import tensorflow
  from tensorflow.python.util import nest
  from seq2seq.configurable import Configurable
label_desc: Use image node_id 2 for calling the ZeroBridge obj's underlying member method code with example usage: obj._create() and returns: zero_state